Horizontal telemeter.



0. EPPENSTEIN.

HORIZONTAL TELF `METER.`

APPLICATION FILED IAN. I5. I9I5.

Patented J u1y 18, 1916.

UNITED STATES PATENT OFFICE.

OTTO EPPENSTEIN, OF JENA, GERMANY, ASSIGNOB T0 THE FIRM OF CARL ZEISS,

JENA, GERMANY.

HORIZONTAL TELEMETER.

Specircation of Letters Patent.

Patented-July is, 191e.

Application filed January 15, 1915. Serial No. 2,488.l

To all whom #may concern Be it known that I, OTTO EPPENSTEIN, a

citizen of the German Empire, residing at.

Jena, Germany, have invented a new and useful Horizontal Telemeter, ofwhich the following is a specification. Y

The invention consists in an improvement in horizontal telemeterscontaining the baseline. Within themselves, in which, as for example inthose according to my copendlng application, Serial Number779,48 8, eachof the two ray pencil systems belongmg to the ends of the base-linepasses through a delecting device, which permits `of the image formedfrom the pencil system and presented to the observer being displacedparallel to the basen-line, and. in which the said two devices arecoupled with each other in such a manner that the two images can bejointly displaced in the direction of the base-line by a small amount.In practice, when manufacturing such instruments, it is hardly possible,to construct the .separate parts of the coupling and to connect themwith the telemeter and the deflecting devices so accurately that, onactuating the said devices, the images will be displaced togetherby-exactly equal amounts, as is requisite for the maintenance of theadjustment ofthe telemeter for all directions of outlook. For

this purpose according to the invention for removing any losses ofadjustment, such as usually occur on the joint displacements of the twoimages taking place, a cam is used, which is jointly displaceable withthe deflecting devices. The nal form of the cam will generally beascertained by setting a telemeter, which is fitted with a cam of a formthat of itself lwould cause no alteration in the reading of therange-scale, at different directions of outlook to an object having aknown distance and by removing. any discrepancies of the value of therange Vbase-line.

placement of the two images by the'defiecb' ing devices, oversteps a'vcertain small amount.

The cammay be used in various ways. For instance, an alteration-in thereading of the range-scale may be caused by itfdirectly, by coupling itwith the said scale or its index in such a manner that an alteration inthe setting ofy the cam causes a relative displacement of the scale andits index, or such an alteration -in the reading can be causedindirectly, by coupling the cam with an arrangement, which alters theangle contained by the axes of the ray pencil systems belonging to 'thetwo ends of the This may, for instance, be effected, by coupling the camwith one of the well-known devices used with telemeters for obtainingfor measuring or 4adjusting purposes an alteration of the said angle;when the deflecting devices serving for the joint displacement of thetwo images are so coupled with oneanother that they can be moved inopposite directions, the cam may be coupled with the delecting devicesin such a manner that an alteration in the setting of the cam causes analteration in the relative position of these devices.

In the four figures of the annexed drawing two constructional examplesof the invention are shown as fitted to one of the two head-parts of atelemeter, Figure 1 being a front elevation of one example and Fig. 2 asection on line 2-2 of Fig. 1 and Fig. 3 being a front elevation of theother example and Fig. 4 a section on line 1r- 4 of Fig. 3. VBothsections are laid through the middle of the ray entrance openingperpendicular to the base-line of the instrument.

IIn the case of both constructional examples the 'cam fulfils-its duty,by effecting an alteration in the angle contained by the axes of the raypencil systems belonging to the two ends of the base-line.

In the first example (Figs. 1 and 2) in front of the light entranceopening a0 of the prism casing a there is disposed a glass wedge 7J,which represents lthe deflecting device. This wedge with its mount 0 isjournaled, so as to be rotatable about the entrance axis of theobjective prism a1 belonging to it, in the bearing body al, which issecured by screws to the casing a, in

such a manner that the plane of its princi i pal section is parallel'tothe said axis. The

mount c is fitted with a worm wheel segment o1, with which a worm eengages, the shaft f of which is rotatable in the bearings d and d1 of'the body d and rotates along with thev glass wedge the deecting deviceat the. other objectwe. side of the telemeter.

The freev end of the yworm shaft-f:` carries a second yworm g, whichengages with aworm.

wheel 72,'. carried by the arm d2 of the bearing body df, on the shaft hof which worm wheel 'principal section parallel to .the entrance l risma1 and is rota. table in a 'ring-shape part d3 of the bearingv body dabout the said axis. Should, on

axis of the objective an alterationof the direction of outlook takingplace, the distance of the tappet Z9 from the axis of rotationl of thedisk i-vary, the glass wedge m will be rotated through a small angle andby this means the direction is altered, in` which the ray pencilsysrvtem passing through it enters the wedge b.

j In the second example (Figs. 3 and there is disposed as deiiectingdevice 1n Ifront of the light entrance opening af of the prism casing aa reflecting prism n, having two reflecting surfaces n. By thisreflecting prism the axial ray passing through it is deviated about aslight angle, as the upper reflecting surface deviates this ray about anangle, which is on a small amount' greater than 45, while the lowerreflecting surface deviates it back again about an angle of 45. Themount 0 of the pair of. reectors n is screwed to a ring p, which isrotatably journaled in a bearing body al fixed to the casing a and isfitted with a worm wheel segment p0. latter there engages a worm e, theshaft f of which rests in the bearings al and d1 and is coupled by meansof a coupling g with a shaft 1*,the driving shaft -of the deflectingdevice at the other end of the `base-line, in

such a mannerthat both deiiecting devices.

are actuated jointly. By means of a pair of bevel wheels, e, s, thedriving wheel s of which is mounted on-the shaft f in such a manner asto allow a slight axial displacement of the latter, a second worm t isrotated, which engages with a worm wheel u.

" This latter worm wheel is'fixed on a shaft u),

which rests 'in the bearings d* and d5and carries a cam c'. A screw c,to one end of which is fixed a tappet fu, which, controlled by a springlv1, slides on the circumference of the camz', and the other end ofwhich With the mentre rests, against the end surface of the free end ofthe shaft f, is disposed in an arm d ef the bearing body d in such amanner that its rotation eects a displacement cf the shaft and of theworm e inthe direction of their longitudinal axis and by this means anadditional rotation of the prism n lying at the end of the telemetershown in the drawing. A spiral spring g Within the coupling g causes theend surface of the fmee end of the shaft f and the screw v to be alwaysin contact with one another. Hence, the cam, the setting of which isaltered alnng with that of the deliecting devices, causes in this casean alteration in the relative pesition of the deflecting devices andthereby an alteration in the angle contained by the axes of the raypencil systems belonging the two ends of the base-line.

.i claim:

1. In a horizontal telemeter containing the base-line Within itself ameasuring device, an ocular system, an ocular reecting system, at eitherside of the said ocular refleeting system an objective lens and adeflecting device, the said delecting devises being adapted to displacein the direction of the base-line the images formed from the ray pencilsystems entering the instrument at either end' of the base-line, jactuating means for eecting a joint displacement cf the two 'images inthe same direction by a joint alteration of the setting of the saiddeflecting devices, a cam adapted to be Dactuated by the said actuatingmeans and translating means actuated by the said cam and connected withone of the said deecting devices for transmitting'motion thereto.

2. In a horizontal telemeter r containing the base-line within itself ameasuring device, an ocular system, an ocular reiiec :if: system, ateither side of the said ocular refiecting system an objective lens and adecil system belonging to one end of the baseline,`and a cam adapted tobeactuated by the said actuating means' and means aetnated by said camand connected with the said additional deiiecting device.

OTTO EPPENSTEET. Witnesses:

PAUL. KRGER, RICHARD HAHN.

